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Old 28th August 2010, 01:38 PM   #1
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Default Sonic differences: 45, 2A3, 300B, 845, 211

Iím wondering if anyone can compare the differences in sonic qualities of the 45, 2A3, 300B, 845, 211 type tubes?

I just finished a 45 amp which I listen to with a pair of Lowthers, and am beginning to think about a new project.

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Old 2nd September 2010, 01:43 PM   #2
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Come on folks I've seen some fine pictures of amps with these tubes.
Surly someone can tell me about 845s and how they compare or differ to 45s, 2A3s, or 300bs.
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Old 2nd September 2010, 02:23 PM   #3
jrenkin is offline jrenkin  United States
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Wow, now that is a question. I suspect you have not gotten response on this because it has a massively broad and subjective answer that has been covered before, currently and again throughout perhaps a billion established threads in this forum.
To address this directly would be simply too daunting I am sure, not to mention so subjective...
I suggest some hours perusing multiple threads and you will find the information there in it's most appropriate form. Good luck.
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Old 2nd September 2010, 03:25 PM   #4
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Each tube has it's own sonic signature. It's up to you to decide which one is right for your ears.
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Old 2nd September 2010, 05:09 PM   #5
kevinkr is offline kevinkr  United States
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Each amplifier design as well as specific implementation has its own sonic signature, each dht type, and different brands/vintages within a given dht type also have their own sonic signature.
A huge number of permutations to deal with, no one has the definitive answer IMO.

Great results can be achieved with any of these types depending on the required power and other specific design goals.
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine

Last edited by kevinkr; 2nd September 2010 at 05:28 PM.
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Old 2nd September 2010, 05:19 PM   #6
Pano is offline Pano  United States
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I think jrenkin deserves a gold star for his answer.
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Old 2nd September 2010, 07:22 PM   #7
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They pretty much all sound similar to each other when the driver topology
and quality of the output transformer are kept constant. That said, you'll
hear larger subjective differences when you vary between, say, someone M6 cored gapped transformer versus some else's nickel cored parafeed transformer. You'll then hear some other subjective differences as you swap
out the driver from, say, RC coupled to IT coupled. With the smaller
tubes (2a3, 45, 845 operated as a 45), you can build a two-stage amplifier
and benefit from the distortion cancellation tricks that can be had with two stages of gain.

Requirements and budgets drive the choice. Lowthers, Klipsch, and the like can definitely budget out and build a 45 or 2A3 amp in a nice, compact footprint. 250V and 60 mA.

People with 90-93 dB efficient speakers would need more power,
and will have to build a larger footprint amp with 300B or 845 at low voltage.
450V and 70mA.

People who want to spend alot of money, presumable to drive an inefficient speaker with a SET amp, will have to build out an 845 or 211 at 1000V, at
high expense, extreme difficulty in parts reliability and amp construction.

I built an 845 amp that runs at typical 300B operating point. At the time,
845's (new) were $39/ea. I'm still running the same pair that I bought in
2003. The motive for low voltage 845 was comparative cheapness compared
to hyped 300B products, and the alleged and now confirmed long life of the thoriated filament tubes. Another motive is that the amplifier just simply looks
cool in my living room - if you're going to take the time to build something,
the build quality and materials and finish should be A+.

-- Jim
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Old 2nd September 2010, 08:51 PM   #8
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IF you are using a ZFB (zero loop feedback) design, then the sound is all over the map. That will vary by tube age, tube manufacture, date of manufacture and manufacturer (brand).

If you are using an amp with feedback, then that will tend to alter the results, but still there are sonic differences based on the same factors.

They are literally all different.

I'd say that the sound groups together around tubes of one type - BUT there is a big difference between "300B" tubes depending on who made it and when. Even Western Electric tubes vary depending on age (which also changes their manufacture and materials slightly).

Also, one would have to compare amps made with the same output iron and topology, and in practice that doesn't happen.

Then too a tube that sounds great in A2 with a given topology might sound like doogie poop in A1 with another topology. Same thing with the iron and power supplies.

How about fixed vs. self bias??

So the answer is simply: there is no simple answer.


PS. gee, isn't that helpful?
_-_-bear -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ]
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Old 2nd September 2010, 10:07 PM   #9
piano3 is offline piano3  United Kingdom
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Nearly all 845, 211 and similar amps use 1000V and more power supplies although I am most interested to read that the member above has built one successfully at 300B operating points. I personally would not be happy having something as lethal as that in my house although I agree that they do look really cool. If I needed that power I would definitely change my speakers. I am sure your 45 amp sounds lovely with your Lowthers.
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Old 2nd September 2010, 10:12 PM   #10
piano3 is offline piano3  United Kingdom
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Actually, I have a 300B SE amp and a good friend has a 2A3 Parallel SE amp with similar circuit topology. For what it is worth(almost nothing) I prefer his and if I were to build something similar(which I would not) I would definitely use 2A3's.
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